Absence of BTK, BCL2, and PLCG2 Mutations in Chronic Lymphocytic Leukemia Relapsing after First-Line Treatment with Fixed-Duration Ibrutinib plus Venetoclax.

PURPOSE: Mutations in BTK, PLCG2, and BCL2 have been reported in patients with progressive disease (PD) on continuous single-agent BTK or BCL2 inhibitor treatment. We tested for these mutations in samples from patients with PD after completion of first-line treatment with fixed-duration ibrutinib plus venetoclax for chronic lymphocytic leukemia (CLL) in the phase II CAPTIVATE study. PATIENTS AND METHODS: A total of 191 patients completed fixed-duration ibrutinib plus venetoclax (three cycles of ibrutinib then 12-13 cycles of ibrutinib plus venetoclax). Genomic risk features [del(11q), del(13q), del(17p), trisomy 12, complex karyotype, unmutated IGHV, TP53 mutated] and mutations in genes recurrently mutated in CLL (ATM, BIRC3, BRAF, CHD2, EZH2, FBXW7, MYD88, NOTCH1, POT1, RPS15, SF3B1, XPO1) were assessed at baseline in patients with and without PD at data cutoff; gene variants and resistance-associated mutations in BTK, PLCG2, or BCL2 were evaluated at PD. RESULTS: Of 191 patients completing fixed-duration ibrutinib plus venetoclax, with median follow-up of 38.9 months, 29 (15%) developed PD. No baseline risk feature or gene mutation was significantly associated with development of PD. No previously reported resistance-associated mutations in BTK, PLCG2, or BCL2 were detected at PD in 25 patients with available samples. Of the 29 patients with PD, 19 have required retreatment (single-agent ibrutinib, n = 16, or ibrutinib plus venetoclax, n = 3); 17 achieved partial response or better, 1 achieved stable disease, and 1 is pending response assessment. CONCLUSIONS: First-line fixed-duration combination treatment with ibrutinib plus venetoclax may mitigate development of resistance mechanisms associated with continuous single-agent targeted therapies, allowing for effective retreatment. See related commentary by Al-Sawaf and Davids, p. 471.

Outcomes in Patients with High-Risk Features after Fixed-Duration Ibrutinib plus Venetoclax: Phase II CAPTIVATE Study in First-Line Chronic Lymphocytic Leukemia.

PURPOSE: The CAPTIVATE study investigated first-line ibrutinib plus venetoclax for chronic lymphocytic leukemia in 2 cohorts: minimal residual disease (MRD)-guided randomized discontinuation (MRD cohort) and Fixed Duration (FD cohort). We report outcomes of fixed-duration ibrutinib plus venetoclax in patients with high-risk genomic features [del(17p), TP53 mutation, and/or unmutated immunoglobulin heavy chain (IGHV)] in CAPTIVATE. PATIENTS AND METHODS: Patients received three cycles of ibrutinib 420 mg/day then 12 cycles of ibrutinib plus venetoclax (5-week ramp-up to 400 mg/day). FD cohort patients (n = 159) received no further treatment. Forty-three MRD cohort patients with confirmed undetectable MRD (uMRD) after 12 cycles of ibrutinib plus venetoclax received randomized placebo treatment. RESULTS: Of 195 patients with known status of genomic risk features at baseline, 129 (66%) had ≥1 high-risk feature. Overall response rates were >95% regardless of high-risk features. In patients with and without high-risk features, respectively, complete response (CR) rates were 61% and 53%; best uMRD rates: 88% and 70% (peripheral blood) and 72% and 61% (bone marrow); 36-month progression-free survival (PFS) rates: 88% and 92%. In subsets with del(17p)/TP53 mutation (n = 29) and unmutated IGHV without del(17p)/TP53 mutation (n = 100), respectively, CR rates were 52% and 64%; uMRD rates: 83% and 90% (peripheral blood) and 45% and 80% (bone marrow); 36-month PFS rates: 81% and 90%. Thirty-six-month overall survival (OS) rates were >95% regardless of high-risk features. CONCLUSIONS: Deep, durable responses and sustained PFS seen with fixed-duration ibrutinib plus venetoclax are maintained in patients with high-risk genomic features, with similar PFS and OS to those without high-risk features. See related commentary by Rogers, p. 2561.

Ibrutinib Plus Venetoclax for First-Line Treatment of Chronic Lymphocytic Leukemia: Primary Analysis Results From the Minimal Residual Disease Cohort of the Randomized Phase II CAPTIVATE Study.

PURPOSE: CAPTIVATE (NCT02910583), a randomized phase II study, evaluates minimal residual disease (MRD)-guided treatment discontinuation following completion of first-line ibrutinib plus venetoclax treatment in patients with chronic lymphocytic leukemia (CLL). METHODS: Previously untreated CLL patients age < 70 years received three cycles of ibrutinib and then 12 cycles of combined ibrutinib plus venetoclax. Patients in the MRD cohort who met the stringent random assignment criteria for confirmed undetectable MRD (Confirmed uMRD) were randomly assigned 1:1 to double-blind placebo or ibrutinib; patients without Confirmed uMRD (uMRD Not Confirmed) were randomly assigned 1:1 to open-label ibrutinib or ibrutinib plus venetoclax. Primary end point was 1-year disease-free survival (DFS) rate with placebo versus ibrutinib in the Confirmed uMRD population. Secondary end points included response rates, uMRD, and safety. RESULTS: One hundred sixty-four patients initiated three cycles of ibrutinib lead-in. After 12 cycles of ibrutinib plus venetoclax, best uMRD response rates were 75% (peripheral blood) and 68% (bone marrow). Patients with Confirmed uMRD were randomly assigned to receive placebo (n = 43) or ibrutinib (n = 43); patients with uMRD Not Confirmed were randomly assigned to ibrutinib (n = 31) or ibrutinib plus venetoclax (n = 32). Median follow-up was 31.3 months. One-year DFS rate was not significantly different between placebo (95%) and ibrutinib (100%; arm difference: 4.7% [95% CI, -1.6 to 10.9]; P = .15) in the Confirmed uMRD population. After ibrutinib lead-in tumor debulking, 36 of 40 patients (90%) with high tumor lysis syndrome risk at baseline shifted to medium or low tumor lysis syndrome risk categories. Adverse events were most frequent during the first 6 months of ibrutinib plus venetoclax and generally decreased over time. CONCLUSION: The 1-year DFS rate of 95% in placebo-randomly assigned patients with Confirmed uMRD suggests the potential for fixed-duration treatment with this all-oral, once-daily, chemotherapy-free regimen in first-line CLL.

Lenalidomide induces long-lasting responses in elderly patients with chronic lymphocytic leukemia.

We evaluated long-term outcomes of 60 patients with chronic lymphocytic leukemia treated with an initial therapy of lenalidomide. At a median follow-up of 4 years, time-to-treatment failure has not been reached and overall survival is 82%. Thirty-five (58%) patients had a response lasting >36 months (long-term responders [LTRs]). Best LTR responses consisted of 25 (71%) complete remissions and 10 (29%) partial remissions. In addition to clinical responses, an increase in IgA, IgG, and IgM levels of >50% from baseline was reported in 61%, 45%, and 42% of LTRs. Normalization in the percentage of CD4+ and CD8+ cells and T-cell numbers was observed in 48%, 71% and 99% of LTRs. Compared with other patients in the study, LTRs had lower baseline plasma levels of ß-2-microglobulin, were more likely to have trisomy 12, and less likely to have deletion 17p.

Phase II study of lenalidomide and rituximab as salvage therapy for patients with relapsed or refractory chronic lymphocytic leukemia.

PURPOSE: Lenalidomide is an immunomodulatory drug active as salvage therapy for chronic lymphocytic leukemia (CLL). We combined lenalidomide with rituximab to improve response rates in patients with relapsed or refractory CLL. PATIENTS AND METHODS: Fifty-nine adult patients (age 42 to 82 years) with relapsed or refractory CLL were enrolled onto a phase II study of lenalidomide and rituximab. Patients had received prior fludarabine-based therapy or chemoimmunotherapy. Rituximab (375 mg/m(2) intravenously) was administered weekly during cycle one and on day 1 of cycles three to 12. Lenalidomide was started on day 9 of cycle one at 10 mg orally and administered daily continuously. Each cycle was 28 days. Rituximab was administered for 12 cycles; lenalidomide could continue indefinitely if patients benefitted clinically. RESULTS: The overall response rate was 66%, including 12% complete responses and 12% nodular partial remissions. Time to treatment failure was 17.4 months. Median overall survival has not been reached; estimated survival at 36 months is 71%. The most common grade 3 or 4 toxicity was neutropenia (73% of patients). Fourteen patients (24%) experienced a grade 3 to 4 infection or febrile episode. There was one episode of grade 3 tumor lysis; one patient experienced renal failure during the first cycle of therapy, and one venous thromboembolic event occurred during the study. CONCLUSION: The combination of lenalidomide and rituximab is active in patients with recurrent CLL and warrants further investigation.

Lenalidomide as initial therapy of elderly patients with chronic lymphocytic leukemia.

The best initial therapy for elderly patients with chronic lymphocytic leukemia (CLL) has not yet been defined. We investigated the activity of lenalidomide as initial therapy for elderly patients with CLL. Sixty patients with CLL 65 years of age and older received treatment with lenalidomide orally 5 mg daily for 56 days, then titrated up to 25 mg/d as tolerated. Treatment was continued until disease progression. At a median follow-up of 29 months, 53 patients (88%) are alive and 32 patients (53%) remain on therapy. Estimated 2-year progression-free survival is 60%. The overall response rate to lenalidomide therapy is 65%, including 10% complete response, 5% complete response with residual cytopenia, 7% nodular partial response, and 43% partial response. Neutropenia is the most common grade 3 or 4 treatment-related toxicity observed in 34% of treatment cycles. Major infections or neutropenic fever occurred in 13% of patients. Compared with baseline levels, we noted an increase in serum immunoglobulin levels across all classes, and a reduction in CCL3 and CCL4 plasma levels was noted in responding patients. Lenalidomide therapy was well tolerated and induced durable remissions in this population of elderly, symptomatic patients with CLL. This study was registered at www.clinicaltrials.gov as #NCT00535873.

Cyclophosphamide, fludarabine, alemtuzumab, and rituximab as salvage therapy for heavily pretreated patients with chronic lymphocytic leukemia.

Patients with relapsed chronic lymphocytic leukemia (CLL) and high-risk features, such as fludarabine refractoriness, complex karyotype, or abnormalities of chromosome 17p, experience poor outcomes after standard fludaradine-based regimens. Alemtuzumab is a chimeric CD52 monoclonal antibody with activity in CLL patients with fludarabine-refractory disease and 17p deletion. We report the outcome for 80 relapsed or refractory patients with CLL enrolled in a phase 2 study of cyclophosphamide, fludarabine, alemtuzumab, and rituximab (CFAR). All patients were assessed for response and progression according to the 1996 CLL-working group criteria. For the intention-to-treat analysis, the overall response rate was 65%, including 29% complete response. The estimated progression-free survival was 10.6 months and median overall survival was 16.7 months. Although we noted higher complete response in high-risk patients after CFAR compared with a similar population who had received fludarabine, cyclophosphamide, and rituximab as salvage therapy, there was no significant improvement in progression-free survival and overall survival appeared worse. CFAR was associated with a high rate of infectious complications with 37 patients (46%) experiencing a serious infection during therapy and 28% of evaluable patients experiencing late serious infections. Although CFAR produced good response rates in this highly pretreated high-risk group of patients, there was no benefit in survival outcomes.

Fludarabine, cyclophosphamide, and rituximab chemoimmunotherapy is highly effective treatment for relapsed patients with CLL.

Optimal management of patients with relapsed/refractory chronic lymphocytic leukemia (CLL) is dictated by patient characteristics, prior therapy, and response to prior therapy. We report the final analysis of combined fludarabine, cyclophosphamide, and rituximab (FCR) for previously treated patients with CLL and identify patients who benefit most from this therapy. We explore efficacy of FCR in patients beyond first relapse, patients with prior exposure to fludarabine and alkylating agent combinations, and patients with prior exposure to rituximab. The FCR regimen was administered to 284 previously treated patients with CLL. Patients were assessed for response and progression by 1996 National Cancer Institute-Working Group (NCI-WG) criteria for CLL and followed for survival. The overall response rate was 74%, with 30% complete remission. The estimated median overall survival was 47 months and median progression-free survival for all patients was 21 months. Subgroup analyses indicated that the following patients were most suitable for FCR treatment: patients with up to 3 prior treatments, fludarabine-sensitive patients irrespective of prior rituximab exposure, and patients without chromosome 17 abnormalities. FCR is an active and well-tolerated therapy for patients with relapsed CLL. The addition of rituximab to FC improved quality and durability of response in this patient population.

What is the best frontline therapy for patients with CLL and 17p deletion?

Chronic lymphocytic leukemia (CLL) is a lymphoproliferative disease with significant variation in disease progression, response to therapy, and survival outcome. Deletions of 17p or mutations of TP53 have been identified as one of the poorest prognostic factors, being predictive of short time for disease progression, lack of response to therapy, short response duration, and short overall survival. The treatment of patients with CLL has improved significantly with the development of chemoimmunotherapy, but this benefit was not pronounced in patients with 17p deletion. We compare various treatment strategies used in these patients, including FCR-like chemoimmunotherapy, alemtuzumab, other antibody combinations, or novel targeted therapies with promising results. Allogeneic stem cell transplantation offers the possibility for long-term disease control in these patients and should be considered early in younger, transplant-eligible patients. The current state of therapy is far from optimal and resources should be applied to studying therapeutic options for patients who have CLL with loss of p53 function.